A wide variety of amorphous metal alloys have been suggested such as described in U.S. Pat. No. 3,856,513. Some of such alloys have been suggested for use in power transformers. Due to their intrinsic magnetic softness and high electrical resistivity, many of the transition metal-metalloid amorphous alloys have a.c. coercivity significantly less than conventional silicon-iron alloys. A significant reduction in the magnetic core losses of power transformers could result in major energy savings.
Perhaps the most serious disadvantage of amorphous alloys as replacements for conventional silicon-iron in transformer cores is the relatively low magnetic saturation induction. It is believed by the industry that formation of the amorphous alloys requires substantial quantities of non-magnetic glass-forming elements such as boron, phosphorus, carbon, or silicon, and this lowers the maximum attainable induction. The highest value of the room temperature flux density reported to date is 16.5 kGauss (kG) for an alloy of Fe.sub.70 Co.sub.10 B.sub.20, wherein the subscript numbers refer to atomic percentages of the elements. However, the inclusion of 10% cobalt renders this alloy extremely costly for large-scale applications. In alloys containing no cobalt, the highest reported value is 16.1 kG for Fe.sub.80 B.sub.20. This value is probably too low to permit large scale economic use in power transformers. A heat treatment under controlled stress is described in U.S. Pat. No. 4,053,333 to enhance the magnetic properties of amorphous metallic alloys.